Laser device with a stepped graded index separate confinement heterostructure

ABSTRACT

Embodiments of the present disclosure are directed towards a laser device with a stepped graded index separate confinement heterostructure (SCH), in accordance with some embodiments. One embodiment includes a substrate area, and an active region adjacent to the substrate area. The active region includes an SCH layer, which comprises a first portion and a second portion adjacent to the first portion. A composition of the first portion is graded to provide a first conduction band energy increase over a distance from multiple quantum wells (MQW) to a p-side of a laser device junction. A composition of the second portion is graded to provide a second conduction band energy increase over the MQW to the p-side distance. The first conduction band energy increase is different than the second conduction band energy increase. Other embodiments may be described and/or claimed.

FIELD

Embodiments of the present disclosure generally relate to the field ofincreasing efficiency in multiple quantum well lasers with a separateconfinement heterostructure.

BACKGROUND

Semiconductor lasers may be used as components in optical transceiversfor digital communications products. For example, silicon photonic chipsuse on-chip lasers as optical sources for digital transmission. It maybe useful for the lasers, and in particular for multiple quantum wells(MQW) lasers, to operate within as small an electrical power budget aspossible, while providing sufficient optical power to span thecommunication link with low bit-error rate. The efficiency of the lasermay therefore be important for the competitiveness of the overalltransmitter.

For example, in the hybrid silicon laser technology, the efficiency ofthe laser depends on the design of the III-V active region gainmaterial, which is bonded to the silicon substrate of the laser device.It is important that the laser design encompass high confinement ofelectrical carriers as well as the optical mode near the multiplequantum wells. For this purpose it is typical to introduce a separateconfinement heterostructure (SCH) in MQW lasers. The SCH typicallyincludes additional p-type and n-type layers with lower refractiveindexes than the central p-type and n-type layers of the active regionof MQW lasers, to provide effective optical confinement. Accordingly,the SCH typically combines low optical index for optical confinementwith high bandgap for electrical confinement.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be readily understood by the following detaileddescription in conjunction with the accompanying drawings. To facilitatethis description, like reference numerals designate like structuralelements. Embodiments are illustrated by way of example and not by wayof limitation in the figures of the accompanying drawings.

FIG. 1 is an example communication system that utilizes a laser devicewith a stepped graded index SCH, in accordance with some embodiments.

FIG. 2 is a front cross-section view of an example structure of a laserdevice with a stepped graded index SCH, in accordance with someembodiments.

FIG. 3 is an example diagram illustrating energy band edges in asemiconductor material provided by a laser device with a stepped gradedindex SCH, in accordance with some embodiments.

FIG. 4 is an example experimental data indicating wall-plug efficiencyand electrical power consumption of the laser with a stepped gradedindex SCH, in accordance with some embodiments.

FIG. 5 schematically illustrates an example computing device including alaser device with a stepped graded index SCH, in accordance with someembodiments.

DETAILED DESCRIPTION

Embodiments of the present disclosure describe techniques andconfigurations for a laser device with a stepped graded index SCH, inaccordance with some embodiments. In embodiments, the laser deviceincludes a substrate (e.g., silicon on insulator (SOI)) area, and anactive region adjacent to the substrate area. The active region includesa separate confinement heterostructure layer, which comprises a firstportion and a second portion adjacent to the first portion.

A composition of the first portion is graded to provide a firstconduction band energy increase over a distance from MQW to a p-side ofa laser device junction. A composition of the second portion is gradedto provide a second conduction band energy increase over the distancefrom the MQW to the p-side of the laser device junction. The firstconduction band energy increase over the distance from the MQW to thep-side is different than the second conduction band energy increase overthe distance from the MQW to the p-side. In embodiments, the laserdevice may comprise an MQW laser.

In the following description, various aspects of the illustrativeimplementations will be described using terms commonly employed by thoseskilled in the art to convey the substance of their work to othersskilled in the art. However, it will be apparent to those skilled in theart that embodiments of the present disclosure may be practiced withonly some of the described aspects. For purposes of explanation,specific numbers, materials and configurations are set forth in order toprovide a thorough understanding of the illustrative implementations.However, it will be apparent to one skilled in the art that embodimentsof the present disclosure may be practiced without the specific details.In other instances, well-known features are omitted or simplified inorder not to obscure the illustrative implementations.

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, wherein like numeralsdesignate like parts throughout, and in which is shown by way ofillustration embodiments in which the subject matter of the presentdisclosure may be practiced. It is to be understood that otherembodiments may be utilized and structural or logical changes may bemade without departing from the scope of the present disclosure.Therefore, the following detailed description is not to be taken in alimiting sense, and the scope of embodiments is defined by the appendedclaims and their equivalents.

For the purposes of the present disclosure, the phrase “A and/or B”means (A), (B), (A) or (B), or (A and B). For the purposes of thepresent disclosure, the phrase “A, B, and/or C” means (A), (B), (C), (Aand B), (A and C), (B and C), or (A, B and C).

The description may use perspective-based descriptions such astop/bottom, in/out, over/under, and the like. Such descriptions aremerely used to facilitate the discussion and are not intended torestrict the application of embodiments described herein to anyparticular orientation.

The description may use the phrases “in an embodiment,” or “inembodiments,” which may each refer to one or more of the same ordifferent embodiments. Furthermore, the terms “comprising,” “including,”“having,” and the like, as used with respect to embodiments of thepresent disclosure, are synonymous.

The term “coupled with,” along with its derivatives, may be used herein.“Coupled” may mean one or more of the following. “Coupled” may mean thattwo or more elements are in direct physical or electrical contact.However, “coupled” may also mean that two or more elements indirectlycontact each other, but yet still cooperate or interact with each other,and may mean that one or more other elements are coupled or connectedbetween the elements that are said to be coupled with each other. Theterm “directly coupled” may mean that two or more elements are in directcontact.

FIG. 1 is an example communication system that utilizes a laser devicewith a stepped graded index SCH, in accordance with some embodiments.The system 100 includes a transmitter chip 102, configured to transmitdata to a receiver chip 140. In embodiments, the transmitter chip 102comprises a photonic integrated circuit (IC) with one or more on-chiplaser devices 104, 106, 108, 110. In embodiments, one or more of thelaser devices 104, 106, 108, 110 may include SCH layers (e.g., SCHstructures 114, 116, 118, 120 respectively) provided according to astepped graded index design, in accordance with embodiments describedherein. It will be understood that the number of on-chip laser devicesmay vary according to technological needs and constraints; the laserdevices 104, 106, 108, 110 with respective stepped graded index SCHstructures 114, 116, 118, 120 are shown for purposes of illustration.

In embodiments, the transmitter chip 102 may further include opticalmodulators 124, 126, 128, 130 optically coupled with the laser devices104, 106, 108, 110 respectively. The outputs of the modulators 124, 126,128, 130 may couple with a multiplexer (MUX) 132. It should beunderstood that the chip 102 (and receiver chip 140) may include othercomponents (e.g., processors, memory, etc.) that are not shown hereinfor ease of explanation.

In operation, the optical signals provided by the laser devices 104,106, 108, 110 may be modulated with electronic data inputs, provided tothe modulators (one of the electronic data inputs 134, provided to themodulator 124, is shown for purposes of clarity). The optical signalscarrying the data information (e.g., 138) may be multiplexed by themultiplexer 132 and the resulting data signal may be provided to anoptical data communication channel 136 (e.g., optical fiber cable) fortransmission. In embodiments, the length of the optical channel 136 mayvary, e.g., from a few meters to a few kilometers.

On the receiver chip 140 side, the optical signal may be de-multiplexedby the demultiplexer (DMUX) 142, and de-multiplexed optical data signals(e.g., 152) may be provided to respective photodetectors 144, 146, 148,150. The photodetectors 144, 146, 148, 150 may convert received opticaldata signals into an electronic form and provide resulting electronicdata signals (e.g., 154) for further processing.

In embodiments, the lasers with stepped graded index SCH (e.g., laser104 with SCH 114) according to the embodiments described herein providefor increased communication speed, lower power consumption, higherconfinement, and higher injection efficiency compared to existingsolutions. In addition or in the alternative to the example system 100described above, the lasers with stepped graded index SCH may be used inoptical transceivers, Light Detection and Ranging (LIDAR), optical andquantum computing systems, and the like.

FIG. 2 is a front cross-section view of an example structure of a laserdevice with a stepped graded index SCH, in accordance with someembodiments.

The structure of the laser device 200 may include a substrate (e.g.,silicon on insulator (SOI)) area 260 and a III-V active region 270disposed adjacent to (e.g., on) the SOI area 260. The SOI area 260 mayinclude multiple layers, some of which are described below. The SOI area260 may include a substrate layer 202 comprising a substrate material ofthe SOI wafer (e.g., silicon). A buried oxide layer (BOX) 204 isprovided on the substrate layer 202 for vertical optical confinement ofthe laser device 200. An optical waveguiding layer 206 is provided onthe BOX layer 204. In embodiments, the optical waveguiding layer 206 mayinclude silicon layer 208 with air gap 210 and silicon rib 212.

The III-V active region 270 includes an n-contact layer 214 provided onthe optical waveguiding layer 206. In embodiments, the n-contact layer214 may comprise the Indium-Phosphide/Indium-Gallium-Aluminum-Arsenide(InP/InGaAsP) semiconductor material. The region 270 may further includean n-type region 216 provided on the n-contact layer 214. The n-typeregion 216 may comprise InP material.

The region 270 may further include multiple quantum wells (MQW) 218 forstimulated emission of light 250 within the laser 200. The MQW 218 maycomprise Aluminum-Gallium-Indium-Arsenide (AlGaInAs).

In embodiments, the region 270 may further include an SCH layer 220disposed adjacent the MQW 218 for confinement of electrons near the MQW218 and vertical confinement of the optical mode. SCH layer 220 maycomprise AlGaInAs material. It should be noted that the materialcompositions for the region 270 are provided by way of example. Othersuitable materials may be used for n-contact layer, MQW, SCH, and othercomponents of the active region of the laser device 200.

In embodiments, the SCH layer 220 is divided into two portions, firstportion 222 and second portion 224, which may be disposed adjacent to(e.g., on top of) first portion 222. Compositions of each portion may beprovided to have the portions be graded differently from each other. Inembodiments, the first and second portions 222 and 224 may be gradedlinearly or in some other manner, e.g., non-linearly, such as, forexample, parabolically. In the context of SCH layer, grading meansgradual change of the composition to accomplish grading of the opticalindex and conduction band edge or overall bandgap of the material of theSCH layer.

For example, the first portion 222 (lower portion of the SCH layer 220in FIG. 2) may be steeply graded, providing rapid increase of thelaser's conduction band energy over distance from n-side (e.g., n-typeregion 216) to p-side (e.g., p-type region 226 described below) of thelaser device 200 junction. The second portion 224 (upper portion) may beshallowly graded, compared to the first portion, providing slowerincrease of the laser's conduction band energy over a distance from MQWinto the p-side of the laser device 200 junction), compared to thegrading of the first portion 222. In other words, the SCH layer 220 maybe stepped graded (e.g., in a linear manner), the first portion 222being the first grading step, and the second portion 224 being thesecond grading step.

For example, the stepped graded SCH layer 220 may be graded as follows.The steep graded portion (e.g., first portion 222) may have a thicknessof about 20 nm, and may be graded from a bandgap of 1.292 eV to 1.390eV. The shallow graded portion (second portion 224) may have a thicknessof about 100 nm, and may be graded from a bandgap of 1.390 eV to 1.415eV.

It will be understood that the above thicknesses and grading values areprovided by way of an example. Different thicknesses and grades of firstand second portions 222 and 224 may be contemplated and used, dependingon particular technological demands to the laser device 200.

For example, the SCH layer 220 may have overall thickness of about 200nm, wherein the first portion 222 may have thickness of about 50 nm andthe second portion 224 may have thickness of about 150 nm. Inembodiments, the desired stepped (linearly) graded SCH layer 220 may beproduced by managing the growth of the layer, such as by varying thecomposition of the material as the layer is fabricated. The steppedlinearly graded SCH layer will be explained in further detail inreference to FIG. 3.

In embodiments, the region 270 further includes a p-type region 226 ofthe laser, which may comprise p-doped Indium-Phosphide (p-InP) claddinglayer. The region 270 further includes a p-contact layer 228 (e.g.,P-InGaAs) disposed on top of the p-type region 226, an insulation layer230 disposed on top of the p-contact layer 228, and a metal layer 234disposed between the contact layer 228 and the insulation layer 230, asshown.

The laser device 200 also includes metal contacts 232 and 233.Specifically, metal contact 232 (N-pad) is disposed on the n-type region216, at least partially inside the insulation layer 230, as shown. Themetal contact 233 (P-pad) is disposed on top of the p-contact layer 228and partially inside the insulation layer 230, as shown.

FIG. 3 is an example diagram illustrating energy band edges in asemiconductor material provided by a laser device with a stepped gradedindex SCH, in accordance with some embodiments. Specifically, diagram300 shows valence band energy curve 302 and conduction band energy curve304 respectively, provided by the stepped graded index design of the SCHlayer of the laser of FIG. 2. The vertical axis Y reflects band energy(not to scale), and the horizontal axis X reflects distance from MQW top-side of the laser device junction (not to scale). The bandgap of thesemiconductor material is engineered to provide the change in conductionband and valence band energy of the III-V material around the quantumwells and p-SCH of the laser device 200, moving from bottom (left sideon x axis) to top (right side on x axis).

Existing solutions include several varieties of the SCH layer design,such as step-index, graded, and parabolic. Step-index typically canoffer high carrier confinement, particularly for a small number ofquantum wells employed in the laser structure. However, the step-indexstructure causes a “notch” in the valence band due to the discontinuitybetween the MQW region and the SCH. This “notch” can hamper theinjection of holes, increasing resistance and contributing to Jouleheating, which then can reduce the laser's wall-plug efficiency. This“notch” also acts like a well for holes, leading to high recombinationcurrent at the interface which further reduces injection efficiency.

Linearly graded and parabolically graded SCH designs provide for thefunneling of hot electrons back to the MQW as they lose energy, andavoid the “notch” described above. However, these designs areaccompanied by reduced confinement and a shallow graded bandgap,particularly near the MQW, which can allow more carriers to escape theMQW region.

In order to achieve high confinement as well as to avoid a large valenceband “notch” and its associated resistance penalty, a stepped gradedindex design according to the embodiments described herein can beemployed. As discussed with reference to FIG. 2, the first portion 222of the SCH layer 220 (FIG. 2) is graded to provide with a steep (e.g.,near-vertical) conduction band edge portion 306, without introducing alarge valence-band notch as would be the case for a stepped indexdesign. For example, the first portion 222 may provide a much largerchange in bandgap over the first 20 nm than over the remaining thicknessof the second portion 224 (referencing FIG. 2). For example, in someembodiments, the band edge portion 306 may be near-vertical relative tothe axis X. Accordingly, the first portion 222 of the SCH layer 220accomplishes high confinement.

The second portion 224 of the SCH layer 220 (disposed adjacent to firstportion 222 as shown in FIG. 2) is compositionally graded to achieve aless steep, but still sloped conduction band edge portion 308. Forexample, as described above, the steep graded portion (first portion222) may have a thickness of about 20 nm, and may be graded from abandgap of 1.292 eV to 1.390 eV. The shallow graded portion (secondportion 224) may have a thickness of about 100 nm, and may be gradedfrom a bandgap of 1.390 eV to 1.415 eV. That corresponds to a change of0.098 eV/20 nm, or 4.9 meV/nm for the steep portion, and 0.025 eV/100nm, or 0.25 eV/nm for the shallow portion. In other words, the gradientof the band edge portion 306 is greater than the gradient of the bandedge portion 308.

The composition of differently graded portions of the SCH as describedherein provides additional carrier recovery by funneling hot carriersback to the MQW as they lose energy. In embodiments, an electronblocking layer or layers may be added for additional confinement,resulting in a notch 310 in the conduction band edge 304

The example embodiments described in reference to FIG. 3 provide forlinear grading of first and second portions of the SCH layer 220.However, stepped linear grading of the individual portions of the SCHlayer are described for purposes of explanation. The individual portions222 and 224 may be graded in a different manner. For example, theindividual portions 222 and 224 may be stepped parabolically graded, orthey may be stepped with linear and parabolic grading respectively, orvice versa, or the like.

The SCH stepped grade design described herein provides for the numerousadvantages compared to existing solutions. For example, the laser withstepped graded index SCH design provides for low resistance andinterface recombination by avoiding a “notch” at the MQW/SCH interface,together with high confinement and efficient hot carrier recovery.Accordingly, high laser efficiency at high power together with lowresistance for high wall-plug efficiency may be accomplished with thelasers according to the embodiments described herein.

In summary, the laser device with the SCH stepped linear grade designprovided according to the embodiments described herein can combine highinjection efficiency, high confinement, and low resistance, enablinghighly efficient operation even at high bias currents and opticalpowers.

FIG. 4 is an example experimental data indicating wall-plug efficiencyand electrical power consumption of the laser with a stepped gradedindex SCH, in accordance with some embodiments. The example data isshown in comparison to the linear graded index SCH laser data collectedacross various design parameters.

The upper graph 402 illustrates the wall-plug efficiency (WPE) as afunction of the bias current Ibias, for different designs of theepitaxial material and different front mirror kappa*length product(FMKL). In the graph 402, curves 410, 412, and 414 are provided for alaser device with the stepped graded index SCH layer, according to theembodiments described herein. Curves 420, 422, and 424 are provided fora laser device with a conventional linear graded index SCH design.

The lower graph 404 indicates the electrical power consumption (Pelec)as a function of the bias current Ibias, for different designs of theepitaxial material. In the graph 404, curves 430, 432, and 434 areprovided for a laser device with the stepped graded index SCH layer,according to the embodiments described herein. Curves 440, 442, and 444are provided for a laser device with a conventional linear graded indexSCH design. As can be seen from the comparison of the curves 410, 412,and 414 with the curves 420, 422, and 424 respectively, the laserdevices with the stepped graded index SCH design have higher wall-plugefficiency than the laser devices with conventional linear graded indexSCH design. Further, as can be seen from the comparison of the curves430, 432, and 434 with the curves 440, 442, and 444 respectively, thelaser devices with the stepped graded index SCH design have lowerelectrical power consumption than the laser devices with conventionallinear graded index SCH design.

FIG. 5 schematically illustrates an example computing device including alaser device with a stepped graded index SCH, in accordance with someembodiments.

The computing device 500 includes system control logic 508 coupled toone or more processor(s) 504; a memory device 512; one or morecommunications interface(s) 516; and input/output (I/O) devices 520. Thememory device 512 may be a non-volatile computer storage chip (e.g.,provided on the die). The memory device 512 may be configured to beremovably or permanently coupled with the computing device 500.

Communications interface(s) 516 may provide an interface for computingdevice 500 to communicate over one or more network(s) and/or with anyother suitable device. Communications interface(s) 516 may include anysuitable hardware and/or firmware. Communications interface(s) 516 forone embodiment may include, for example, a network adapter, a wirelessnetwork adapter, a telephone modem, and/or a wireless modem. Forwireless communications, communications interface(s) 516 for oneembodiment may use one or more antennas to communicatively couple thecomputing device 500 with a wireless network. In embodiments,communication interface(s) 516 may include, or couple with, atransceiver, such as transmitter chip 102 of FIG. 1, including one ormore laser devices (e.g., 104, 106, 108, 110) with SCH stepped gradedindex design, according to the embodiments described herein.

For one embodiment, at least one of the processor(s) 504 may be packagedtogether with logic for one or more controller(s) of system controllogic 508. For one embodiment, at least one of the processor(s) 504 maybe packaged together with logic for one or more controllers of systemcontrol logic 508 to form a System in Package (SiP). For one embodiment,at least one of the processor(s) 504 may be integrated on the same diewith logic for one or more controller(s) of system control logic 508.For one embodiment, at least one of the processor(s) 504 may beintegrated on the same die with logic for one or more controller(s) ofsystem control logic 508 to form a System on Chip (SoC).

System control logic 508 for one embodiment may include any suitableinterface controllers to provide for any suitable interface to at leastone of the processor(s) 504 and/or to any suitable device or componentin communication with system control logic 508. The system control logic508 may move data into and/or out of the various components of thecomputing device 500.

System control logic 508 for one embodiment may include a memorycontroller 524 to provide an interface to the memory device 512 tocontrol various memory access operations. The memory controller 524 mayinclude control logic 528 that may be specifically configured to controlaccess of the memory device 512.

In various embodiments, the I/O devices 520 may include user interfacesdesigned to enable user interaction with the computing device 500,peripheral component interfaces designed to enable peripheral componentinteraction with the computing device 500, and/or sensors designed todetermine environmental conditions and/or location information relatedto the computing device 500. In various embodiments, the user interfacescould include, but are not limited to, a display, e.g., a liquid crystaldisplay, a touch screen display, etc., a speaker, a microphone, one ormore digital cameras to capture pictures and/or video, a flashlight(e.g., a light emitting diode flash), and a keyboard.

In various embodiments, the peripheral component interfaces may include,but are not limited to, a non-volatile memory port, an audio jack, and apower supply interface. In various embodiments, the sensors may include,but are not limited to, a gyro sensor, an accelerometer, a proximitysensor, an ambient light sensor, and a positioning unit. The positioningunit may additionally/alternatively be part of, or interact with, thecommunication interface(s) 516 to communicate with components of apositioning network, e.g., a global positioning system (GPS) satellite.

In various embodiments, the computing device 500 may be a mobilecomputing device such as, but not limited to, a laptop computing device,a tablet computing device, a netbook, a smartphone, etc.; a desktopcomputing device; a workstation; a server; etc. The computing device 500may have more or fewer components, and/or different architectures. Infurther implementations, the computing device 500 may be any otherelectronic device that processes data.

According to various embodiments, the present disclosure describes anumber of examples.

Example 1 is a laser device, comprising: a substrate, and an activeregion adjacent to the substrate, wherein the active region includes aseparate confinement heterostructure (SCH) layer, which comprises afirst portion and a second portion adjacent to the first portion. Acomposition of the first portion is graded to provide a first conductionband energy increase over a distance from multiple quantum wells (MQW)to a p-side of a laser device junction, and a composition of the secondportion is graded to provide a second conduction band energy increaseover the distance from the MQW to the p-side of the laser devicejunction. The first conduction band energy increase over the distancefrom the MQW to the p-side is different than the second conduction bandenergy increase over the distance from the MQW to the p-side.

Example 2 includes the laser device of Example 1, wherein the firstportion is linearly graded.

Example 3 includes the laser device of Example 1, wherein the secondportion is linearly graded.

Example 4 includes the laser device of Example 1, wherein the firstportion has a thickness of about 20 nm, and is graded from 1.292 eV to1.390 eV.

Example 5 includes the laser device of Example 4, wherein the secondportion has a thickness of about 100 nm, and is graded from 1.390 eV to1.415 eV.

Example 6 includes the laser device of Example 1, wherein the laserdevice is a multiple quantum well (MQW) laser.

Example 7 includes the laser device of Example 1, wherein the firstconduction band energy increase over the distance from the MQW to thep-side of the laser device is greater than the second conduction bandenergy increase over the distance from the MQW to the p-side of thelaser device.

Example 8 includes the laser device of Example 1, wherein the SCH layercomprises Aluminum-Gallium-Indium-Arsenide (AlGaInAs) material.

Example 9 includes the laser device of any of Examples 1 to 8, whereinthe laser device comprises an integrated circuit.

Example 10 includes a computing device, comprising: a processor, and acommunication interface coupled with the processor to provide datacommunication for the processor, wherein the communication interfaceincludes a transceiver with a laser device to provide the datacommunication. The laser device includes a substrate area and an activeregion adjacent to the substrate area. The active region includes aseparate confinement heterostructure (SCH) layer, which comprises afirst portion and a second portion adjacent to the first portion,wherein a composition of the first portion is graded to provide a firstconduction band energy increase over a distance from multiple quantumwells (MQW) to a p-side of a laser device junction, and a composition ofthe second portion is graded to provide a second conduction band energyincrease over the distance from the MQW to the p-side of the laserdevice junction. The first conduction band energy increase over thedistance from the MQW to the p-side is greater than the secondconduction band energy increase over the distance from the MQW to thep-side.

Example 11 includes the computing device of Example 10, wherein thefirst portion is linearly graded.

Example 12 includes the computing device of Example 11, wherein thesecond portion is linearly graded.

Example 13 includes the computing device of Example 10, wherein thelaser device is a multiple quantum well (MQW) laser.

Example 14 includes the computing device of Example 10, wherein thetransceiver comprises an integrated circuit.

Example 15 includes the computing device of any of Examples 10 to 14,wherein the computing device comprises one of: a laptop, a server, or adesktop.

Example 16 includes an integrated circuit, comprising a laser device toprovide the data communication. The laser device includes a silicon oninsulator (SOI) area and an active region adjacent to the SOI area. Theactive region includes a separate confinement heterostructure (SCH)layer, which comprises a first portion and a second portion adjacent tothe first portion. A composition of the first portion is graded toprovide a first conduction band energy increase, and a composition ofthe second portion is graded to provide a second conduction band energyincrease. A first gradient of the first conduction band energy isgreater than a second gradient of the second conduction band energy.

Example 17 includes the integrated circuit of Example 16, wherein thefirst portion is linearly graded.

Example 18 includes the integrated circuit of Example 17, wherein thefirst portion has a thickness of about 20 nm, and is graded from 1.292eV to 1.390 eV.

Example 19 includes the integrated circuit of any of Examples 16 to 18,wherein the second portion is linearly graded.

Example 20 includes the integrated circuit of Example 19, wherein thesecond portion has a thickness of about 100 nm, and is graded from 1.390eV to 1.415 eV.

Various embodiments may include any suitable combination of theabove-described embodiments including alternative (or) embodiments ofembodiments that are described in conjunctive form (and) above (e.g.,the “and” may be “and/or”). Furthermore, some embodiments may includeone or more articles of manufacture (e.g., non-transitorycomputer-readable media) having instructions, stored thereon, that whenexecuted result in actions of any of the above-described embodiments.Moreover, some embodiments may include apparatuses or systems having anysuitable means for carrying out the various operations of theabove-described embodiments.

The above description of illustrated implementations, including what isdescribed in the Abstract, is not intended to be exhaustive or to limitthe embodiments of the present disclosure to the precise formsdisclosed. While specific implementations and examples are describedherein for illustrative purposes, various equivalent modifications arepossible within the scope of the present disclosure, as those skilled inthe relevant art will recognize.

These modifications may be made to embodiments of the present disclosurein light of the above detailed description. The terms used in thefollowing claims should not be construed to limit various embodiments ofthe present disclosure to specific implementations disclosed in thespecification and the claims. Rather, the scope is to be determinedentirely by the following claims, which are to be construed inaccordance with established doctrines of claim interpretation.

What is claimed is:
 1. A laser device, comprising: a substrate; and anactive region adjacent to the substrate, wherein the active regionincludes a separate confinement heterostructure (SCH) layer, whichcomprises a first portion and a second portion adjacent to the firstportion, wherein a composition of the first portion is graded to providea first conduction band energy increase over a distance from multiplequantum wells (MQW) to a p-side of a laser device junction, and acomposition of the second portion is graded to provide a secondconduction band energy increase over the distance from the MQW to thep-side of the laser device junction, wherein the first conduction bandenergy increase over the distance from the MQW to the p-side isdifferent than the second conduction band energy increase over thedistance from the MQW to the p-side.
 2. The laser device of claim 1,wherein the first portion is linearly graded.
 3. The laser device ofclaim 1, wherein the second portion is linearly graded.
 4. The laserdevice of claim 1, wherein the first portion has a thickness of about 20nm, and is graded from 1.292 eV to 1.390 eV.
 5. The laser device ofclaim 4, wherein the second portion has a thickness of about 100 nm, andis graded from 1.390 eV to 1.415 eV.
 6. The laser device of claim 1,wherein the laser device is a multiple quantum well (MQW) laser.
 7. Thelaser device of claim 1, wherein the first conduction band energyincrease over the distance from the MQW to the p-side of the laserdevice is greater than the second conduction band energy increase overthe distance from the MQW to the p-side of the laser device.
 8. Thelaser device of claim 1, wherein the SCH layer comprisesAluminum-Gallium-Indium-Arsenide (AlGaInAs) material.
 9. The laserdevice of claim 1, wherein the laser device comprises an integratedcircuit.
 10. A computing device, comprising: a processor; and acommunication interface coupled with the processor to provide datacommunication for the processor, wherein the communication interfaceincludes a transceiver with a laser device to provide the datacommunication, wherein the laser device includes a substrate area and anactive region adjacent to the substrate area, wherein the active regionincludes a separate confinement heterostructure (SCH) layer, whichcomprises a first portion and a second portion adjacent to the firstportion, wherein a composition of the first portion is graded to providea first conduction band energy increase over a distance from multiplequantum wells (MQW) to a p-side of a laser device junction, and acomposition of the second portion is graded to provide a secondconduction band energy increase over the distance from the MQW to thep-side of the laser device junction, wherein the first conduction bandenergy increase over the distance from the MQW to the p-side is greaterthan the second conduction band energy increase over the distance fromthe MQW to the p-side.
 11. The computing device of claim 10, wherein thefirst portion is linearly graded.
 12. The computing device of claim 11,wherein the second portion is linearly graded.
 13. The computing deviceof claim 10, wherein the laser device is a multiple quantum well (MQW)laser.
 14. The computing device of claim 10, wherein the transceivercomprises an integrated circuit.
 15. The computing device of claim 10,wherein the computing device comprises one of: a laptop, a server, or adesktop.
 16. An integrated circuit, comprising: a laser device toprovide the data communication, wherein the laser device includes: asilicon on insulator (SOI) area; and an active region adjacent to theSOI area, wherein the active region includes a separate confinementheterostructure (SCH) layer, which comprises a first portion and asecond portion adjacent to the first portion, wherein a composition ofthe first portion is graded to provide a first conduction band energyincrease, and a composition of the second portion is graded to provide asecond conduction band energy increase, wherein a first gradient of thefirst conduction band energy is greater than a second gradient of thesecond conduction band energy.
 17. The integrated circuit of claim 16,wherein the first portion is linearly graded.
 18. The integrated circuitof claim 17, wherein the first portion has a thickness of about 20 nm,and is graded from 1.292 eV to 1.390 eV.
 19. The integrated circuit ofclaim 16, wherein the second portion is linearly graded.
 20. Theintegrated circuit of claim 19, wherein the second portion has athickness of about 100 nm, and is graded from 1.390 eV to 1.415 eV.